Summary Cannabis use during pregnancy has increased substantially, in conjunction with widespread decriminalization/legalization, changing public perceptions about harm, and evidence of cannabis's antiemetic properties. Prior outcomes research on prenatal marijuana exposure is narrow in scope and may have limited relevance to medicinal users, as these older studies included research participants with polysubstance use (e.g. tobacco, alcohol, illicit drugs). In addition, prior research also likely underestimated potential risks of cannabis use during pregnancy because modern strains are 3x more potent than they were 30 years ago. We propose to study brain development in infants exposed in utero to cannabis using state-of-the-art MRI and behavioral measures that we have developed in our studies of infants at high-risk for developing autism spectrum disorder. Cutting-edge neuroimaging techniques have been shown to identify brain changes and subtle behavioral differences before outward symptoms are visible. By focusing on infancy, we aim to characterize cannabis-induced brain and behavioral changes while minimizing environmental effects that contribute to outcomes at older ages. To test our hypotheses, we will recruit 35 pregnant women who are using cannabis to alleviate morning sickness and 35 pregnant women who are using prescribed medication for morning sickness. When infants reach 6 months of age, they will receive extensive neuropsychological assessment and multi-modal imaging (fMRI odor task, resting state fMRI, magnetic resonance spectroscopy, and diffusion tensor imaging) under natural sleep.